Surgical devices are used in various open, endoscopic, and laparoscopic surgeries to transect tissue volumes and blood vessels. The devices generally include jaws for grasping tissue therebetween and a cutting mechanism that is advanced through the grasped tissue to transect it. The cutting mechanism can be designed to travel within a track formed in one or both jaws of the cutting mechanism. In some instances the devices can also be used to seal tissue volumes and blood vessels being transected, for instance by applying electrical energy to the grasped tissue to seal it before tissue transection is completed. For example, various mono-polar and bi-polar radio frequency (RF) surgical instruments and surgical techniques have been developed for sealing tissue volumes and blood vessels. Electrodes can be disposed on a face of one or both of the jaws and can apply energy to the grasped tissue to promote hemostasis.
Some of these surgical devices incorporate mechanical linkages between the closure actuator and the jaws such that when a user manipulates the closure actuator, e.g., by manually squeezing a trigger, the jaws close. This can give a user control over the amount of compression applied to tissue in the jaws because the user receives tactile feedback when operating the closure actuator. However, high manual forces may be necessary for a user to operate the closure actuator in a mechanically-based device and there are limits as to the amount of compression that can be achieved manually.
Further, when operating a tissue compression device, an amount of compression applied by the jaws to the tissue affects hemostasis. By increasing the amount of compression applied to the target tissue, the flow of blood can be limited, which can decrease the time necessary to achieve hemostasis. However, applying too much compression to manipulate tissue without sealing the tissue can result in damage to the tissue if the applied compression/clamping force is too high. Additionally, applying too much compression can artificially reduce impedance of the tissue as a result of being overcompressed and too thin. Overcompression can also make it difficult to apply resistive heating to tissue using an RF tissue sealing device. An optimal amount of force depends on various factors, including the type and thickness of tissue disposed between the jaws.
Accordingly, there remains a need for improved surgical devices and methods for compressing tissue and sensing tissue and other objects grasped by the device.